Refractory article



Sept. 27, 1932. G. s. FuLcHER REFRACTORY ARTICLE Filed Der). l5, 1927 INVENToR Gordon xS/cet A ORNEYJ.

Patented Sept. 27, 1932 UNITED STATES PATENT OFFICE GORDON S. FULCHER, OF CORNING, NEW YORK, ASSIGNOR TO COR-NING- GLASS WORKS, F CORNING, NEW YORK, A CORPORATION OF NEW vYORK REFRACTORY ARTICLE Application led December 15, 1927. Serial No. 240,265.

This invention relates to improvements in refractories, and more particularly to the manufacture of solid cast refractory articles free from internal flaws or voids.

Cast refractory articles `to which this invention relates are produced by melting together raw materials, such as ores consisting largely of alumina, silica, zirconia and the like, after which the fused product is poured into molds of suitable shapes and sizes, and annealed to relieve internal strains and prevent. cracking of the articles, as described and claimed in Patent 1,615,750, issued to me on January 25, 1927.

Owing to the nature of the materials used, there is a wide variation between the volume of the fused product in its liquid and solid states, so that upon solidification a` substantial shrinkage takes place with the result that U liaws and voids are frequently formed within the casting.v These are commonly known in the art as pipe and are objectionable as they reduce the life and the specific gravity of the casting.

Due to the way in which the molten refractory material solidifies, and its tendency to produce a uniform external crust about the casting upon contact with the cooler mold surfaces, articles having a greater depth than the side of the gate opening could not heretofore be poured free from pipe with a single pouring, as the material solidified at the gate and closed the passage therethrough before the material in the mold had completely solidified. This prevented the molten material in the front from entering the mold during the solidification and shrinkage of the remaining liquid contents thereof.

It is an object of the present invention to produce a cast refractory article which will be solid and non-porous throughout and will have long life and utility.

Another object of the invention is to accelerate the solidilication of the casting so that the gate will remain open until the castin'g has completely solidified.

A feature of the invention is the partial filling of the mold with solidified refractory material, which reduces the depth of the molten refractory material contained therein so that even though the diameter of the gate opening is less than the depth of the desired casting, a solid cast refractory article may be obtained with a single pouring.

Another feature is the reinforcement of the article and the prevention of cracks which may occur in one part thereof from being communicated to another part.

The above and other objects may be attained by practicing the method constituting the subject matter of the present invention, which will be fully set forth and claimed in the following specification, and illustrated in the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view through a mold prepared .to receive molten refractory material, and showing a core of solidified refractory material therein;

Fig. 2 is a transverse sectional view, on the line 2 2 of Fig. 1, after pouring the molten refractory material thereinto and before it solidifies;

Fig. 3 is an inverted perspective view of the core employed to partially fill the mold prior to the pouring of the article; and

\Fig. 4 is a perspective view of an article produced by practicing this invention.

Referring to the drawing in detail, the mold 10 may be of any preferred construe` tion and material, but it has been determined that slabs 11 formed of sand, bonded with linseed oil and baked, are Well suited for this purpose. These slabs are connected together in any suitable manner, as by the use' of mold lpaste or the like, and may be'made in any preferred size and shape to produce the desired article. fn the presentvinstance the mold 10 is shown prepared to produce a refractory block such as is used to line glass melting tanks.

In the preferred embodiment of my invention, a core 12, of the material from which the refractory article is to be made, is cast in a suitable mold (not shown), and its physical characteristics are the same as those of the refractory article in which it is to be embedded. In its present form the core 12 consists of a rectangular body 12 provided with integrally formed legs 13 by which it is supported in spaced relation to the bottom of the mold 10.

A container 14 of any suitable size and shape is provided with layers of heat insulating bricks 15 upon which the mold 10 rests. If desired, a slab 11 of similar construction to the slab 11 which forms the bottom of the mold may be interposed between the latter and the upper layer of bricks 15. After placing the mold in the container, heat insulating bricks 16 are positioned between the sides of the mold and the sides of the container, and .the spaces between the bricks 16 are filled with a suitable heat insulating material 21, such as silocel.

After preparing the mold 10 as above set forth the core 12 is placed therein as shown in Fig. 1, a top slab 17, provided with a central opening 18 through which the molten refractory material is poured, is placed on the mold. A similar apertured slab 19 is then disposed upon the top slab 17 with the openings in registration, and a font mold 20, into which the liquid refractory material is to be poured, is mounted on the slab 19. The space between the font mold and the walls of the container is then lled with insulating material 21, and the refractory material is poured into the mold.

In some instances the insertion of the core into the mold without preheating will prove satisfactory, but certain advantages will be experienced when the core is preheated, transferred to the mold while hot, and the molten material poured into the mold before the core has cooled -appreciably. Preheating the core reduces the tendency of gas to collect and form pockets between the core and the surrounding material. Moreover, a larger core may be used in proportion to the size of the block since the chilling effect of the core is reduced in proportion as the temperature is raised.

In the preferred embodiment of my invention, in which the core is of the same material as the rest of the refractory article, even when it is preheated to a temperature half as great as the melting temperature no bond is effected between the solid and liquid refractory materials and, as a consequence, in the finished article there is a crack or seam separating the core from the surrounding ma` terial. While such a casting is 'not as resistant to corrosion as one which is homogeneous and free from cracks, it has a decided advantage from a mechanical point of view in that the core provides a reinforcement for the block, for even though a crack may develop therein, it will not extend through the core and the latter will function to hold the parts together. Since the core is slowly cooled in the center of the block, it is certain to be thoroughly annealed and free from cracks.

While it is preferable that the core be made of the same material as the rest of the block,

it is sometimes more convenient to use a core made by sintering together refractory material having similar properties. Such a core will perform the same function as a cast core provided the melting temperature of the material is approximately as high as that of the material cast around the core, so that no bond is effected between the core and the cast material. v

Placing a core in the mold as above described has the effect of decreasing the depth of the liquid poured around the core, thereby lessening the amount of liquid material which -has to solidify.

The molten refractory material is poured into the mold, through the font mold, to completely fill the mold and to practically fill the font mold, and as the material in the mold solidifies and shrinks additional material will flow into it from the font mold. In this way a suiiicient supply of liquid refractory material is provided to insure the production of a solid casting which fills the mold. Upon contacting with the mold and core surfaces the liquid begins to set, and owing to the symmetrical disposition of the core the depth of the liquid is less than the diameter of the gate opening, so that the liquid within the mold will solidify before the gate does.

After the liquid has completely solidified, the font is broken away and the completed article, such as a tank block 22 (Fig. 4) may be removed from the mold for annealing, or this may be accomplished by slowly cooling it in the mold. After the annealing the surfaces of the article may be subjected to any suitable dressing process to make its various faces smooth and true.

While in the foregoing there has been set forth the preferred embodiment of the invention, it is to be understood that minor changes in the procedure may be resorted to within the scope of the following' claims.

-Refractory is used herein to designate a substance which, when used in a furnace of high temperature, will forv a prolonged period, successfully withstand the temperatures encountered and will resist the abrasion and corrosion at the places used.

I claim:

1. An annealed cast refractory article for use in contact with molten glass, said articles being provided with a reinforcing core of reractory material having the same composition as the article.

2. An annealed refractory article for use in contact With molten glass which includes a core ofrefractory material surrounded by alayer of cast refractory material the core and layer being composed ofthe same materials.

3. An annealed cast refractory article forl use in contact with molten glass provided with a pre-formed annealed core of cast re- K fractory material having the same composition as the article.

GORDON S. FULCHER. 

